The present invention relates generally to an electrical connection for use in a machine having at least one removable unit to operate properly. More particularly, it relates to an electrical connection having two elements, one on each of the main frame of the machine and one on the removable unit, one element comprising a plurality of resiliently flexible conductive fibers in a brush-like configuration the other element being a continuous conductive contact surface for the fibers. In a preferred embodiment, the machine is an electrostatographic printing machine.
In electrostatographic reproducing apparatus commonly used today, a photoconductive insulating member is typically charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image contained within the original document. Alternatively, a light beam may be modulated and used to selectively discharge portions of the charged photoconductive surface to record the desired information thereon. Typically, such a system employs a laser beam. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with developer powder referred to in the art as toner. Most development systems employ developer which comprises both charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles. During development, the toner particles are attracted from the carrier particles by the charged pattern of the image areas of the photoconductive insulating area to form a powder image on the photoconductive area. This toner image may be subsequently transferred to a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure.
In order to minimize maintenance costs by permitting the operator to replace warn out or exhausted processing units in electrostatographic apparatus, it has been suggested to incorporate one or more processing units of the apparatus in disposable or removable cartridges or units. In this way the operator can readily remove each cartridge when its operational life has been exhausted and insert a new cartridge. In addition, it also provides the advantage of being able to use less expensive functional features such as the photoreceptor drum in a conventional copier. Typically, these processing cartridges include an imaging member such as a rotatable drum or a endless belt together with one or more of a charge corotron, a developing device and cleaning device. For further description of such machine architecture attention is directed, for example to U.S. Pat. No. 3,985,436 to Tanaka et al., U.S. Pat. No. 4,462,677 to Onoda, U.S. Pat. No. 4,470,689 to Moramora et al., and U.S. Pat. No. 4,460,267, U.S. Pat. No. 4,556,308 to Hoppner et al..
In these commercial applications, it is of course necessary to distribute power, high voltage and/or logic signals between the main frame of the machine and the removable processing unit or cartridge. Traditionally, this has taken the form of utilizing conventional wires and wiring harnesses in each machine to distribute power and logic signals between the main frame of the machine and the removable processing unit. For example, conventional plug and socket arrangements have been used which can be either manually connected or joined automatically on insertion of the unit into the main frame. This automatic joining requires precision positioning and alignment of the unit on insertion with very low tolerance for error. Typically locating members such as pins, rails, etc. are used to insure proper positioning which adds to the manufacturing cost of the machine. In addition, conventional wires and wiring harnesses are flexible and therefore, do not lend themselves to automated assembly such as with the use of robots further leading to increased manufacturing costs. While certain other electrical contacts have been proposed, they suffer certain deficiencies. For example, the use of two conventional metal plate contacts such as two spring biased metal tabs one on each of the main frame and the removable unit in addition to requiring the precision positioning and alignment discussed above can be rendered unreliable after only a short period of use in the hostile machine environment by having the contacting surfaces contaminated by dirt, toner or other debris. Furthermore, such metal contacts tend to oxidize forming an insulating layer on the contact surface thereby further degrading the reliability and performance of the contact.